Operator overloading allows the programmer to define how operators (such as +, -, ==, =, and !) should interact with various data types.
Because operators in C++ are implemented as functions, operator overloading works very analogously to function overloading.
Constructor:
Constructors are typically used to initialize member variables of the class to appropriate default values.
In the class , we can define public or private for its data member (or method).
The data member can only be used by method of class if we define the type of data member is public.
In C++, classes are very much like structs, except that classes provide much more power and flexibility.
In C++, when we declare a variable of a class, we call it instantiating the class. The variable itself is called an instance of the class. A variable of a class type is also called an object.
Union is like strucuture but it can only assign one member one time , and a anonymous union is a union without class name .
Anonymous can help us save memory space , because operation system would allocate the largest memory space of largest
Reference is a alias of a variable , it can be used to instead of pointer sometimes.
C++ references differ from pointers in several essential ways:
Sometimes we may generate the functions which have the same function
but have different argument or return type.
cout, clog and cerr are pre-defined objects defined in ostream.
The iostream class inherits from both ostream and istream
We can use the operator , dec , oct , and hex to decide which format we want.
for example:
Sometimes , we may want to find word in string.
we can use string::find to achieve this purpose.
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